This Cannon is very Good For suppression Fire or Just Straight up and Blowing the socks of them. wait a few seconds and then connect the other Redstone Machine To the Front dispensers and run immediatly away cause the Ultimate TNT Cannon is about to fire. To fire connect the redstone in between the back redstone machine and the dispensers in the back of the TNT cannon. once all the Dispensers are filled the cannon is ready to fire. Fill all the dispensers with TNT UNTIL FULL as this cannon goes through TNT like no tomorrow.
After you Have finished the second redstone machine Wire them up to the Cannon so one redstone machine fires one set of dispensers and the other fires another, but Do not Connect the Redstone wires to the cannon, it should look like this in the end.